Thumbstick attachment for a controller



FIG. 1 is a front perspective view of a thumbstick attachment for a controller showing our new design;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a left side view thereof.

The broken line showing of the unshaded circular region of the thumbstick attachment for a controller in FIG. 3 is for environmental purposes only and forms no part of the claimed design. 

CLAIM The ornamental design for a thumbstick attachment for a controller, as shown and described. 